Traffic controlling system for railroads



July 11, 1939: WHITEHQRN 2,166,083

TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed Jan. 30, 1936 lllllllllllllnllll l FIIIII IIIIIIIL n I vi 0 \n e T U M m T 0 MW W mR A 5 A m Y B Patented July 11, 1939 1 UNITED STATES PATENT OFFICE TRAFFIC CONTROLLING SYSTEM FOR RAILROADS ter, N. Y.

Application January 30, 1936, Serial No. 61,565

12 Claims.

Thisinvention relates in general to railway signalling systems and it more particularly pertains to the blinking .or flashing of a regular color light for an additional indication such as a call-on 5 signal.

One feature of this invention comprises means for switching the usual low speed caution or yellow light at a signal location from its usual controlling circuit to a source of interrupted current 1 for causing the light to flash for displaying a callon signal.

Further objects, purposes and characteristic features of this invention will appear as the description progresses, reference being had to the 15 accompanying drawing which shows, solely by way of example, a preferred form and one modification which the invention can assume.

,In the operation of trains in signalling territory, accidents have been known to occur due to a mis- 20 intepretation of the call-on signal. It is therefore proposed, in accordance with this invention, to make use of a rapidly flashing light to designate a call-on signal,

In the accompanying drawing, Fig. 1 illustrates 25 the apparatus and circuits employed in the preferred form of this invention. Fig. 2 illustrates a modified form of flasher which may be substituted for the flasher of Fig. 1.

Referring to Fig. 1, the reference character 3 30 designates the track rails of a railway along which trafilc normally moves from left to right as indicated by the arrow, and which rails are divided by insulated joints 4 to form a track section.- A turn-out or passing siding is illustrated as being 35 associated with the main track by means of a track switch controlled by switch machine SM, but it will be understood that the present invention is not limited to such a layout, since it is applicable to any portion of signalling territory m where call-on signals are required.

Signals l and IA are located at the entrance end of the illustrated track section, which signals are the usual high and low speed signals provided for controlling traffic over the track switch in an east bound direction. Signals 2 and 2A are provided to control traffic in a west bound direction, but since the control of these signals is immaterial for an understanding of the present invention the circuits of these signals are omitted for the sake m of simplicity. The illustrated signals are preferably controlled in part by traffic conditions and in part by an operator located at a central control oflice or ,a tower, in accordance with conditions existing in connection with the territory '55 governed by the illustrated signals.

Signals I and IA for controlling traflic in an east bound direction are controlled by the operator through the medium of signal control relay SZ and an associated signal lever SGL connected by a line circuit. The switch machine is controlled 5 by the operator through the medium of relay WZ and associated lever SML connected by a separate line circuit. The local circuits for controlling the operation of the switch machine are not shown since these circuits form no part of the present invention.

The position of the track switch is indicated by the usual polar neutral switch repeating relay WP, which is controlled by a polarized circuit governed by point detector contacts jointly operated by the track switch and the switch machine. When the tract switch is in its normal position, relay WP is energized with current of one polarity for picking up its neutral contact and for actuating its polar contact to the left hand position as. illustrated in the drawing. When the track switch is in its reverse position, relay WP is energized with current of the opposite polarity for picking up its neutral contact and for actuating its polar contact to its right hand dotted position, When the track switch is unlocked or in operation, relay WP is de-energized.

Signal stick relay SGS is provided when stick signals are required to prevent the call-on signal from clearing automatically behind the train. The control of this relay is such that the operator must operate the signal lever to its center position before attempting to clear the call-on signal for a following train movement.

Relay T is the usual track relay associated with the illustrated track section and since this section is assumed to be unoccupied, this relay is shown in its energized condition.

Local signal control relays ISG and IASG are provided for controlling signals l and IA respectively. The detailed operation. of these relays will be explained in the following specification. Call-on signal relay CSG is for the purpose of causing yellow lamp Y to flash to provide a call-on signal.

Slow-acting relay SA is provided for checking purposes, that is this relay prevents the false steady illumination of lamp Y in the event of a failure of flashing relay FR.

The flashing of the yellow lamp is assumed to be controlled (in Fig. 1) by a suitable flasher relay FR. One type of such relay may be such as. disclosed in the patent to O, S. Field No. 1,969,065 issued August 7, 1934. From the diagrammatic illustration of this relay it will be understood that potential applied to wire 40 energizes the left hand winding of the relay because of the short-circuit across the hight hand winding at contact In. The relay will therefore actuate its armature for switching the contacts to their opposite positions, which in turn short-circuits the left hand winding of the relay and allows the right hand winding to become energized for switching the contacts back to the positions illustrated in the drawing. It will thus be observed that relay FR will automatically operate its contacts to alternate positions when relay CSG closes its front contact H.

The modification illustrated in Fig. 2 makes use of the signal control relay IASG and the call-on signal relay CSG of Fig. 1, with the exponent 2 added. Yellow lamp Y and red lamp R correspond to lamps Y and R of Fig. 1. The flasher relay FR and the checking relay SA of Fig. 1 are replaced by transformer TF, relay PR rectifier RC and rectifier RC in Fig. 2 and it will be explained how the checking feature is provided in Fig. 2 without the use of the slow-acting relay illustrated in Fig. 1.

Instead of showing the actual connections to the terminals of suitable sources of current, symbols have been employed to represent such terminals, The symbols (13+) and (B) have been employed to designate the opposite terminals of a suitable source of current having a center or intermediate tap designated (CN); and the circuits with which these symbols are employed may have current flowing in either direction depending upon the terminal which is employed in combination with tap (ON). The symbols and have been employed to designate the opposite terminals of a suitable source of current and the circuits with which these symbols are employed always have current flowing in the same direction.

It is believed that the operation and usefulness of the present invention will be best understood by further description being set forth from the standpoint of operation.

Operation Normal c0ndz'tions.The track relay T is normally energized according to the usual practice. Similarly, relay WP is energized with a particular polarity in accordance with the normal locked condition of the track switch which actuates the contacts of this relay to the positions illustrated.

Switch control relay W2 is energized over a circuit extending from (ON), winding of relay WZ, line conductor [2 and contact of lever SML in its left hand position to (B-). Current flowing over this circuit actuates the contacts of relay WZ to the positions illustrated.

Relay SZ is normally d e-energized because of the center, open circuit position of lever SGL. Signal stick relay SGS is normally energized over a circuit extending from back contact 54 of relay SZ, front contact I5 of relay T and winding of relay SGS to A stick circuit is closed for relay SGS extending from front contact it of relay SGS', front contact l5 of relay T and winding of relay SGS to The other relays and the lamps associated with signals l and IA are all de-energized, with the exception of red lamp R which is energized over a circuit extending from back contact ll of relay lSG and lamp R to and lamp R which is energized over an obvious circuit extending through back contact 29 of relay IASG.

It will be understood that the actuation of lever SML to its right hand dotted position reverses the current flow over line conductor I2 for switching the polar contacts of relay WZ to their right hand dotted position, certain of these contacts (not shown) controlling the operation of the switch machine to its reverse position. It will likewise be understood that the actuation of lever SGL to the right energizes line conductor [3 in such a direction that relay SZ positions its polar contacts to their right hand dotted positions and picks up its neutral contacts. Also, the actuation of lever SGL to its left hand dotted position causes current to flow over line conductor l3 in the opposite direction for energizing relay S2 to cause it to pick up its neutral contacts and to position its polar contacts to their left hand positions.

Right home distant relay RHD is illustrated with its neutral contact picked up and with its polar contact actuated to the left, it being assumed that the circuit of this relay which is controlled by traffic in advance is energized with current of the proper polarity for so positioning these contacts. The control circuits for relay RI-ID, which are controlled by traffic in advance, are not shown since it is believed well understood in the art how this relay is energized for positioning its contacts as illustrated in Fig. 1 when it is safe for green lamp G to be illuminated, and how the current is reversed through its winding for positioning its polar contact to the right when it is safe for lamp Y to be illuminated.

Control of signals-It will first be assumed that the operator of the control machine desires to allow a train to proceed in an east bound direction over the main track, with which the illustrated track switch is associated. To do this, lever SML will be left in its illustrated normal position for maintaining the contacts of relay WZ in their illustrated positions and for maintaining the track switch in its normal locked condition.

Signal lever SGL will be actuated to its lefthand dotted position (east), which closes an obvious circuit over line conductor I3 for energizing relay SZ in a direction which will maintain its polar contacts in their illustrated positions and which will pick up its neutral contacts. A circuit is now closed for picking up relay ISG which extends from front contact l8 of relay SGS, front contact l9 of relay WZ, front contact 20 of relay WP, contact 2| of relay WP in its left hand position, contact 22 of relay WZ in its left hand position (indicating correspondence between the switch control relay W2 and the switch position indicating relay WP), front contact 23 of relay SZ, contact 24 of relay SZ in its left hand posi" tion, front contact 25 of relay RED and winding of relay ISG to The operation of contact ll of relay ISG puts out lamp R and closes a circuit for lighting lamp G by way of front contact ll, contact 26 of relay RHD in its left hand position and lamp G to In the event that traffic conditions in advance are such that relay RHD has its polar contacts positioned to the right, then the signal clearing circuit for signal I will be the same as above described except that lamp Y will be lighted because of contact 25 of relay RHD being in its right hand dotted position.

When the train enters the illustrated track section it will de-energize track relay T, thereby opening the circuit of relay SGS at contact l5, whereupon signal relay ISG will be de-energized because of open front contact I8 and the green or yellow light (as the case may be) will be de" energized and the red light will be lighted because of the return to normal of contact I! of relay SG.

It will now be assumed that the operator of the control machine desires to admit a train into the passing siding of the illustrated track section.

Lever SML will consequently be actuated to its right hand clotted (reverse) position for actuating the polar contacts of relay WZ to their right hand positions, which controls the switch machine by means of circuits not shown for controlling the operation of the track switch to its reverse locked position. Lever SGL will again be front contact 20 of relay WP, contact 22 of relay WZ in its right hand dotted position, contact 2I of relay WP in its right hand dotted position, front contact 21 of relay 82, contact 28 of relay SZ in its left hand position and winding of relay IASG The picking up of relay IASG puts out the red lamp B because of open back contact 29 and closes a circuit for lighting yellow lamp Y extending from front contact 29 of relay IASG,

back contact 30 of relay CSG and lamp Y to It will be obvious that the occupancy of the track section will drop relay T for de-energizing relay SGS which, because of open front contact I8, drops relay IASG which puts out yellow lamp Y and again energizes red lamp R In both of the above instances, when the train leaves the track section with which relay T is associated, the energization of this relay closes a circuit at its front contact I for stick relay SGS, but this circuit is not complete until the operator restores the signal lever to its center position for de-energizing relay SZ and closing its back contact I4. When relay SGS is picked up, then its stick circuit including its front contact I5 provides a means for maintaining this relay in its picked up position independent of signal lever SGL but dependent upon track relay T.

From the above explanation it is believed obvious how signals 2 and 2A for controlling trafhe in a west bound direction are controlled when the polar contacts of relay SZ are actuated to their right hand dotted positions by the actuation of lever SGL to its right hand dotted position. Since this control is immatrial for an understanding of the present invention, the detailed circuits for signals 2 and 2A are omitted.

Flashing call-on signal.-It was pointed out above how the usual low speed signal IA is controlled to govern tra-fiic onto the illustrated turnout track section. A typical example of a train movement for which the call-on signal indication is given in accordance with the present invention will now be pointed out.

It will be assumed that two east bound trains on the main track are to make a meet with a west bound train standing on the siding. The operator controls the switch machine by means of lever SML and clears signal I by means of lever SGL in the manner previously described. When the first east bound train passes signal I and drops track relay T, relay SGS is de-energized, which in turn drops relay ISG to cause signal I to indicate stop. When the first east bound train advances into the next section in advance, right home distant relay RHD is deenergized (circuits not shown) and closes its back contact 25 which connects the call-on signal relay CSG to the circuit to be controlled when relay SGS again closes its front contact I8.

The entrance of the first train into the next section is reported to the distant operator by the operation of the communication system in the usual way by means not shown, but clearly described in detail in the patent to S. N. Wight No. 2,082,436 granted June 1, 1937. This reporting of the first east bound train to the operator indicates that he may permit the second east bound train to advance into the block on the main track opposite the siding (in the assumed example). He therefore restores signal control lever SGL to its mid-position, which de-energizes relay S2 for closing a pick-up circuit at its back contact I4 for relay SGS. When the operator notes that the first train has cleared the detector track circuit, lever SGL may then be moved back to the position to again clear the east bound signals. Ihis again operates relay SZ and, since relay SGS is now picked up, the above described circuit through its front contact I8 is complete for energizing relay CSG, since back contact 25 of relay RHD is now closed as is also the front contact 3'? of the directional stick relay iS. This relay I S was picked up by the first east-bound train passing the signal I, and is still held stuck up because the first train is still occupying the section in advance of this signal I as is also manifest by the relay RHD being down.

The energization of relay CSG closes the above described circuit for causing the intermittent operation of flashing relay FR. Each time that contact 3| of relay FR is actuated to its lower position a circuit is closed for energizing relay SA which extends from front contact II of relay CSG, contact 3i of relay FR in its lower position and winding of relay SA to relay SA is of the slow releasing type it will maintain its contacts in their picked up positions during the intermittent operation of the flashing relay.

The call-on indication (flashing of yellow lamp Y is now given by means of a circuit extending from front contact II of relay CSG, contact 3! of relay PR in its upper position, front contact 32 of relay SA, front contact 30 of relay CSG and lamp Y to is intermittently closed in its upper position, lamp Y is intermittently energized. After the second train has advanced and cleared the detector track circuit (as indicated to the operator by means of the communication system), the track switch may be reversed and signal 2A may be cleared for the west bound train in the example assumed.

When relay CSG is energized to give a call-on indication, the opening of front contact 25 of relay RHD opens the energizing circuit of relay lSG so that signal I cannot be cleared. In other words, when contact 25 of relay RI-ID establishes the circuit to call-on relay CSG it opens the circuit to relay ISG- which controls the clearing of signal I.

When the main track opposite the siding is occupied by a west bound train, then the signal I cannot be cleared because of open front contact, 70

I8 of relay SCI-S, which relay is de-energized by the dropping of track relay T. Signal IA likewise cannot be cleared to give an improper callon indication when the main track opposite the siding is occupied by a west bound train, because Since Since contact 3| of relay FR of open front contact !8 of relay SGS which prevents the picking up of relay CSG.

It was previously mentioned that all the detailed circuits are not shown, such as those of the home relays and various stick relays which are usually employed in practice. It is believed, however, Well to mention that relay CSG cannot be picked up to give an improper call-on signal when a west bound train is approaching signal 2, for example, but has not yet entered the section of track with which relay T is associated. This is because stick relay is will remain de-energized under this condition because relay is is picked up only by an east-bound train passing signal i, so that relay CSG cannot be picked up because of open front contact 3? of relay IS. Relay is is controlled in any proper manner, such for example as disclosed in Ernest B. Kempster, Jr. Patent No. 2,042,663, issued June 2, 1936.

It will of course be understood that, when the low speed or lower arm signal M. is cleared, whether for a call-on indication or for a train movement onto the siding, the operating rules require that the train accepting the signal indication shall proceed at low speed prepared to stop short of an obstruction ahead.

If desired, the same arrangement for providing a low speed or call-on indication may be used in connection with west bound signals 2 and 2A.

Ihe purpose of relay SA is to prevent an improper steady illumination of lamp Y in case of failure of the flashing relay. For example, in the event that the flashing relay should stop operating with its contacts in their lower positions relay SA will be maintained energized over the circuit including front contact H of relay CSG, but lamp Y will not be energized because of the open condition of the upper point of contact 39. In the event that the flasher relay stops operating with its contacts in the positions illustrated in the drawing, then relay SA will be deenergized and the circuit for lamp Y will be open at front contact In this event a circuit is closed for lighting red lamp R which extends from back contact 3% of relay SA, front contact of relay CSG and lamp R to Fig. 2 modificatiom-The modification illustrated in Fig. contemplates substituting transformer TF, flashing relay PR rectifier RC and rectifier RC for flashing relay FR and checking relay SA of Fig. 1.

When call-on signal relay CSG (corresponding to relay CSG of Fig. l) is picked up a circuit is closed for energizing the primary of transformer TE and relay FR in multiple extending from back contact mil of relay lAEiG front contact ifil of relay C8 3 back contact it? of relay PR and the windings of the transformer and relay PR in multiple to Relay BR picks up and opens this multiple circuit, then the relay de-energizes and closes the circuit, and so on, thus intermittently energizing and de-energizing the primary winding of transformer TF.

This intermittent energization of the primary winding induces a current in the secondary winding of the transformer, which current is permitted to flow in one direction by means of the half-wave rectifier arrangement, including rectifiers RC and RC through front contacts tilt and it? of relay CS'Ci to lamp W. This intermittent energizaticn of the circuit including lamp Y causes the lamp to flash as a call-on indication.

In Fig. 2, the low speed red lamp is normally lighted over a circuit extending from (-1-), back contact Hill of relay IASG (corresponding to relay IASG of Fig. 1), back contact l0! of relay 086% and lamp R to When signal relay EASC} is picked up, the red lamp is extinguished and the yellow lamp is lighted over a circuit extending from front contact I00 of relay lASG back contact HM of relay CSG lamp Y and back contact I03 of relay CS6: to When call-on relay CSG is picked up to flash lamp Y lamp R is extinguished at open back 2 contact NH.

It will be observed that the flashing arrangement of Fig. 2 is of the self-checking type, that is no separate checking relay is required, such as relay SA of Fig. l. The operation of this checking feature (in both figures) is predicated on the theory that no light, rather than an improper steady light should be the result of a failure in the operation of the flasher relay. In Fig. 2, if

the flasher relay stops operating no current will.

1. In a traffic controlling system for railroads,

a track switch at the end of a passing siding, a high speed and a low speed signal governing traffie toward said siding and being governed by traffic, means controlled in accordance with the occupied condition of a block in advance for governing said high speed signal, a signal control lever operable to clear the high or the low speed signal dependent upon the position of the track switch, a normally quiescent flasher for intermittently energizing said low speed signal, said lever and traific conditions causing said flasher to intermittently operate, a slow acting checking relay, and means including said checking relay for preventing the steady energization of said low speed signal in the event of the failure of the flasher to operate intermittently in response to said manual control.

2. In an interlocking system, they combination with a plurality of levers of a control machine free to be actuated to any position at any time; a high and a low wayside signal associated with one of said levers and located at a distant way station; a track switch associated with another of said levers and located at said way station; a traffic controlling means, a circuit controlled by said one lever in one of its positions and by said traific controlled means when a block in ad- Vance of the signal is unoccupied, for steadily energizing said high signal, said circuit including contacts indicating that said track switch and said another lever are in non-conflicting positions; and additional means including part of said circuit and said contacts and operative when said block in advance is occupied for intermittently energizing said low signal to constitute a call-on signal.

3. In a traflic controlling system for railroads, a track switch at the end of a passing siding, a high speed signal and a low speed signal governing traific over said switch toward said siding respectively along the main track and the siding, means responsive to the occupancy of a block in advance of said signals for governing said high speed signal, a manually controlled device effective in one position to hold said signals at stop, means controlled by said device in a second position for clearing said high speed signal or said low speed signal for traffic over said track switch in its normal or reverse positions respectively, and automatic means controlled in part by said device in said second position and in part by the occupied condition of said block in advance, for clearing said low speed signal for trafiic over said track switch in its normal position in a manner distinguishing from the clearing of said low speed signal for traflic over said track switch in its reverse position.

4. In a traffic controlling system for railroads, a track switch at the end of a passing siding movable to normal and reverse positions, a high speed signal and a low speed signal governing trafiic over said track switch toward said siding, means responsive to the occupancy of a block in advance of said signals for governing said high speed signal, a manually controlled device effective in a first position to hold said signals at stop, means controlled by said device in a second position and by the track switch in normal position, and ineffective when said block in advance is occupied, for clearing said high speed signal for traffic over said track switch in its normal position, means controlled by said device in the second position, and by the track switch in reverse position, and effective irrespective of the occupancy of said block in advance, for clearing said low speed signal for traflic over said track switch in its reverse position, and means controlled by said device in the second position, and by the track switch in normal position, only when said block in advance is occupied, for distinctively clearing said low speed signal for traflic over said track switch in its normal position.

5. In a trafflc controlling system for railroads, a track switch at the end of a passing siding and movable to normal and reverse positions, a high speed signal and a low speed signal for governing traffic over said track switch toward said siding respectively along the main track and the siding track, means responsive to the occupancy of a block in advance of said signals and to the track switch in normal position for governing said high speed signal, a manually controlled device effective in a first position to hold said signals at stop, means controlled by said device in a second position and by the track switch in normal position, and ineffective when said block in advance is occupied, for clearing said high speed signal for traffic over said track switch in its normal position, means controlled by said device in the second position and by the, track switch in reverse position and effective irrespective of the occupany of said block in advance, for clearing said low speed signal for traffic over said track switch in its reverse position, and means controlled by said device in the second position and by the track switch in normal position, and then only when said block in advance is occupied, for clearing said low speed signal for traffic over said track switch in its normal position, said last mentioned means including means for operating the low speed signal in a manner distinctive from its operation when cleared for traffic over said track switch in its reverse position.

6. In a traflic controlling system for railroads, a track switch at the end of a passing siding movable to normal and reverse positions, a high speed signal and a low speed signal governing traffic over said track switch toward said siding, means responsive to the occupancy of a block in advance of said signals and to the track switch in normal position for governing said high speed signal, a manually controlled device effective in a first position to hold said signals at stop, means controlled by said device in a second position and to the track switch in normal position and ineffective when said block in advance is occupied, for clearing said high speed signal for traffic over said track switch in its normal position, means controlled by said device in the second position and to the track switch in reverse position and effective irrespective of the occupancy of said block in advance, for clearing said low speed signal for traffic over said track switch in its reverse position, and means controlled by said device in the second position and by the track switch in normal position, and then only when said block in advance is occupied, for clearing said low speed signal for traflic over said track switch in its normal position, said last mentioned means including means for intermittently operating said low speed signal.

'7. In a traflic controlling system for railroads, a track switch at the end of a passing siding, a high speed signal and a low speed signal governing traffic toward said siding along the main track and the siding track, respectively, manual means movable from a stop to a control position, circuit means controlled by the manual means for steadily energizing said signals in accordance with the position of the track switch, means controlled in accordance with the occupied condition of a block in advance of the signal location for governing said high speed signal, a normally inactive flasher for intermittently energizing said low speed signal, said manual means being effective at times, dependent upon trams conditions adjacent the track switch, when maintained in the control position after having been in the stop position for causing said flasher to intermittently operate, a checking means for the flasher, made active only during operation of the flasher, to check against failure of the flasher to operate, and circuit means including said checking means for preventing the steady energization of said low speed signal in the event of the failure of the flasher to operate intermittently.

8. In a trafflc controlling system for railroads, in combination, a passing siding including a track switch, a high speed signal and a low speed signal at the switch for governing traiflc over the switch respectively on the main track and the siding, a. manually operable lever movable to a position to clear the signals, a flasher including a transformer, means including the flasher for intermittently energizing the transformer, and traflic controlled means effective when the switch is set for the main track for at times making the lever effective to energize the flasher and connect the low speed signal to the secondary of the transformer.

9. In a traffic controlling system for railroads, in combination, a passing siding including a track switch, a high speed signal and a low speed signal at the switch for governing traffic over the switch respectively on the main track and the siding, a manually operable lever movable to a position to clear the signals, a flasher including a transformer, means including the flasher for intermittently energizing the transformer, traffic controlled means effective when the switch is set for the main track for at times making the lever effective to energize the flasher, and connect the low speed signal to the secondary of the transformer, and a rectifier unit in series with the transformer secondary, whereby to flash the low speed signal and constitute a call-on signal.

10. In an interlocking system, in combination, a track layout including a track switch, and a main track and a turnout track controlled by the switch, two signals for the track, one for the main track and the other for the turnout, a signal lever movable to an operated position to clear one or the other of the signals by steadily energizing them, dependent upon the position of the track switch if a block in advance of the switch is unoccupied, and means for clearing one of said signals, by flashing the same, by the lever dependent upon occupancy of said block in advance.

11. In an interlocking system, in combination, a track layout including a track switch, and a main track and a turnout track controlled by the switch, two signals, a high speed and a low speed one for respectively governing traffic over the main and turnout tracks, a signal lever movable to an operated position to steadily energize one or the other of the signals dependent upon the position of the track switch, and means for intermittently energizing the low speed signal by the lever dependent upon occupancy of a block in advance of the switch, and the position of the switch for the main track, to thus constitute a main track call-on signal.

12. In a traffic controlling system for railroads, a track switch at the end of a passing siding, a high speed signal and a low speed signal for governing traffic over said switch toward said siding and respectively along the main track and the siding track, means responsive to the occupancy of a block in advance of said signals for automatically governing said high speed signal, a manually controlled device effective in one position to hold said signals at stop, means controlled by said device in another position for clearing said high speed signal or said low speed signal, by steady energization thereof, dependent upon whether said track switch is in its normal or reverse positions respectively, and automatic means controlled by occupancy of said block in advance and cooperating with said device in said other position, when the track switch is in its normal position, for clearing said low speed signal by flashmg the same, whereby to constitute a main track call-on signal.

ARTHUR R. WHITEHORN; 

